The invention relates to a method of preventing overloading of the central controller of a telecommunication system, more specifically a telephone exchange of the type commonly referred to as the stored program controlled (SPC) type.
The invention further relates to an arrangement for performing the method.
In the present telecommunication systems some provisions are of a common and centralized construction, so that only limited numbers of these systems are sufficient. This imposes restrictions on the processing capacity of the system. In systems which comprise a central controller, use is made of the central processor for all connections and connection requests. Owing to the limited quantity of processor time, queues of, for example, telephony tasks are formed. In the event of growing waiting times the required response time can no longer be satisfied, while in the most serious case calls will fail. As processor time is also consumed by unsuccessful calls, the number of successfully processed calls will decrease even further.
In order to avert an imminent overloading of the central controller it is known to predict the number of calls which may be accepted in a subsequent period on the basis of the processor load in a preceding period and the number of calls accepted in that preceding period. In order to prevent excessive fluctuations caused by fluctuations in the number of calls, a limit is imposed on the increase or decrease, as the case may be, of the number of calls which may be accepted in the subsequent period. Owing to the inertia of this control the processor capacity is not optimally utilized and that more specifically at the instant at which this capacity is required to its full extent.
It is an object of the invention to provide a method of preventing overloading of the central controller by means of which in a simple, fast and reliable way an imminent overload is detected and thereafter averted, and by means of which the lowest possible number of calls are refused.